This application is the national phase under 35 U.S.C. xc2xa7 371 of PCT International Application No. PCT/CH00/00045 which has an International filing date of Jan. 31, 2000, which designated the United States of America and was not published in English.
The invention relates to a method for controlling a hydraulic elevator and to a hydraulic elevator device.
Hydraulic elevators are employed advantageously in residential and industrial buildings. They can serve for the vertical transport of persons and/or freight.
U.S. Pat. No. 5,522,479 discloses a control unit for a hydraulic elevator, in which there are two pressure sensors, one of which is arranged on that side of a nonreturn valve facing the pump, while the other is installed on that side of the nonreturn valve facing the hydraulic drive cylinder. The signals from the two pressure sensors are fed to a controller which determines the rotational speed of the electric motor driving the pump. The speed of the elevator traveling up and down is thereby regulated via the quantity of hydraulic oil conveyed per unit time.
U.S. Pat. No. 5,040,639 discloses a valve unit for an elevator, which is assigned a pressure sensor by means of which the pressure in the line leading to the hydraulic drive of the elevator can be detected. Compensation of the pressure prior to the starting phase becomes possible with the aid of this pressure sensor. Moreover, the main valve is assigned a lifting sensor which is required in order to obtain information or, the flow of the hydraulic oil in the starting phase of an upward travel of the elevator.
WO-A-98/34868 discloses a method and a device for controlling a hydraulic elevator, in which the speed of the elevator car can be detected by means of a flowmeter. In this case, with the aid of the signal from this flowmeter, either the rotational speed of the electrical motor driving the pump is controlled or regulated or the opening position of a valve is varied, depending on the operating situation. A changeover of the control variable therefore takes place during the movement of the car. Careful coordination of the control and regulating parameters is consequently a precondition for operation which is as jolt-free as possible, and this necessitates a considerable outlay.
Moreover, such a flowmeter supplies a signal relating to the movement of the elevator car only when the elevator car has already been set in motion. Consequently, the actual start-up operation, which, however, is highly essential to traveling comfort, cannot be regulated.
The object on which the invention is based is to specify a method and device, in which the entire operation, from standstill up to maximum speed and to standstill again, can be controlled or regulated reliably, while the outlay in terms of control and regulation is at the same time to be minimal, to be precise dispensing with additional means determining the thrbughLlow quantity of the hydraulic oil.
Said object is achieved, according to the invention, in a method of the generic type, and, in a device.